JP2014241574A - Reception power estimation device and reception power estimation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately estimate reception power at an arbitrary point, without inputting layout or quality of material of an obstruction such as furniture.SOLUTION: A reception power estimation device 100 comprises: a delay profile estimation unit 101 for estimating a delay profile on the basis of reception power of a plurality of paths actually measured in a space including an indoor space in which an obstruction is provided; a path transmission loss extraction unit 102 for calculating a transmission loss for each path on the basis of the estimated delay profile and reception power of the path in the case of assuming that the space is a free space; a mesh transmission loss estimation unit 104 which divides the indoor space into meshes and calculates an estimation value of a transmission loss for each mesh on the basis of the calculated transmission loss for each path; and a reception power estimation unit 105 for calculating an estimation value of reception power at an arbitrary point in the space, on the basis of the estimation value of the transmission loss value for each mesh.

Description

  The present invention relates to a received power estimation apparatus and a received power estimation method.

  In recent years, with the spread of self-employed indoor wireless communication systems such as a wireless local area network (LAN), interference with adjacent access points and terminals under the access has become a problem. In order to reduce these interferences, it is necessary to design an appropriate communication area of its own access point (hereinafter referred to as “AP”) while avoiding interference to the communication area of adjacent access points. Communication area design is the setting of appropriate transmission power and determination of the antenna installation position. Design the communication area accurately in a home environment where the influence of shadowing by furniture and other shielding objects varies greatly depending on the antenna installation position. Therefore, it is necessary to estimate indoor propagation characteristics at an arbitrary antenna installation position. Further, since propagation fluctuations due to furniture are unique to each building / room, it is necessary to estimate propagation characteristics unique to each building / room.

  There are roughly three methods for estimating propagation characteristics unique to each building / room. The first estimation method is a method of installing an antenna at a measurement point and actually measuring the received power, and the second estimation method is a method of calculating the received power using a statistical model. Is a method of simulating radio wave propagation using building / indoor modeling built on a computer and calculating received power. Since the first estimation method using actual measurement cannot measure other than the antenna installation location, it is difficult to estimate the propagation characteristics of an arbitrary location necessary for communication area design. In addition, the second estimation method using the statistical model is difficult to estimate the propagation characteristics with high accuracy. Therefore, a method for limiting the antenna installation position and correcting the calculated value of the statistical model with the actual measurement value has been proposed. . However, in a home environment where the propagation characteristics vary greatly depending on the antenna installation position, it is difficult to estimate the propagation characteristics of an arbitrary place necessary for communication area design. On the other hand, in the third estimation method using computer simulation, the position of the transmitting / receiving antenna can be arbitrarily moved on the computer. Therefore, if modeling is accurately performed by CAD (computer aided design) software for each building / room, communication area design is possible. It is possible to accurately estimate the propagation characteristics of an arbitrary place necessary for the measurement.

  The computer simulation of received power generally uses a FDTD (Finite Difference Time Domain method) method and a ray tracing method. In the FDTD method, Maxwell's partial differential equation is approximated in terms of time and space, and the electric field strength is obtained by solving in the time domain, and the received power at an arbitrary place can be estimated. Although the FDTD method has high estimation accuracy, since the electromagnetic field analysis is performed for each unit of a fraction of the wavelength, the amount of calculation depends on the size of the region to be estimated. Generally, since the size of a building / room is several orders of magnitude larger than the wavelength, there is a problem that estimation of the propagation environment requires a huge amount of computation. On the other hand, the ray tracing method regards the elementary waves of radio waves as rays and geometrically traces the ray trajectory from the transmission point to the reception point. Based on the result, the electric field strength of each elementary wave at the reception point is calculated. Calculated using geometric optics theory. Since the calculation time of the ray tracing method does not depend on the wavelength, it is suitable for estimating propagation characteristics in buildings and indoors.

  FIG. 22 is a block diagram illustrating a configuration of a reception power estimation apparatus 900 according to the related art (for example, see Non-Patent Document 1). In the figure, a received power estimation apparatus 900 includes a received power estimation unit 901. The reception power estimation unit 901 is a position of a reception point / transmission point terminal (hereinafter referred to as “reception power estimation terminal”), a transmission parameter of the reception power estimation terminal, furniture, etc. The layout data of the shield and the material of the shield are input, and the received power is estimated on the computer using the ray tracing method.

  FIG. 23 is a block diagram illustrating a configuration of a reception power estimation unit 901 of the related art. The reception power estimation unit 901 includes a ray trace calculation unit 902, a propagation loss calculation unit 903, and a reception power calculation unit 904. The ray trace calculation unit 902 regards the radio wave radiated from the transmission point on the spherical surface as a ray, and geometrically determines the ray trajectory based on the layout data of the shielding object such as furniture and the position of the received power estimation terminal. Trace and calculate and output the path from the transmission point to the reception point. The propagation loss calculation unit 903 uses the ray path output from the ray trace calculation unit 902, the material of the shielding object, and the transmission frequency to determine the transmission coefficient, reflection coefficient, diffraction coefficient, and attenuation amount due to distance (for each path). (Propagation loss) is calculated and output. The reception power calculation unit 904 calculates reception power at the reception point using the attenuation output from the propagation loss calculation unit 903, the transmission antenna gain obtained from the transmission parameter, the reception antenna gain, and the transmission power.

Next, the operation of the conventional received power estimation apparatus 900 will be described.
First, use CAD (Computer Aided Design) software to create a layout for shielding objects such as furniture, receive power estimation terminal position indicating the position of the received power estimation target terminal, AP, etc., shielding material, and transmission Reception power estimation terminal transmission parameters indicating antenna gain, reception antenna gain, transmission power, transmission frequency, and the like are input to reception power estimation section 901. The ray trace calculation unit 902 regards the radio wave radiated from the transmission point on the spherical surface as a ray, and geometrically traces the ray trajectory based on the layout data of the shielding object such as furniture and the received power estimation terminal position. And outputs a path from the transmission point to the reception point.

  The propagation loss calculation unit 903 calculates a transmission coefficient, a reflection coefficient, a diffraction coefficient, and an attenuation amount due to a distance for each path from the ray path output from the ray trace calculation unit 902, the shielding material, and the transmission frequency. Output. The reception power calculation unit 904 calculates the reception power at the reception point using the attenuation output from the propagation loss calculation unit 903 and the transmission antenna gain, reception antenna gain, and transmission power included in the transmission parameter data. Output. In this way, the layout data of the shielding object, the position of the terminal / AP for estimating the reception power, the material of the shielding object, the transmission antenna gain, the reception antenna gain, the transmission power, and the transmission frequency can be determined at any place by the ray tracing method. Received power can be obtained.

Next, operations of the above-described propagation loss calculation unit 903 and reception power calculation unit 904 will be described in detail using mathematical expressions. i is the number of the ray, h is the number of the wall, p is the number of the diffraction point, the number of times the i-th ray that has reached the receiving point is reflected by the h-th wall is W _{i, h} , and the i-th ray is the h-th X _{i, h} , the number of times the i-th ray is diffracted by the h-th wall, and Y _{i, h the} number of times the i-th ray is reflected by the h-th wall. Coefficients R _{i, h, l} , transmission coefficient T _{i, h, m} , i-th ray diffracted n-th on h-th wall when i-th ray transmitted m-th on h-th wall D _{i, h, n} , and the total distance from the transmission point of the i-th ray to the first diffraction point is s _{i, 1} , and the p-th diffraction point from the (p−1) -th diffraction point of the i-th ray. the total distance to the diffraction point of up to _{s i, p,} the transmit power _{P t,} the transmit antenna gain _{G t,} a receiving antenna gain _G r, The signal frequency f, light velocity c, and the wave number k (= 2π / λ, λ is the wavelength) When, i-th ray of the electric field strength _{E i,} the propagation loss _{L i,} the received power _{P r,} respectively, the following equation ( It is calculated by 1), (2), (3). Note that j is an imaginary unit, Re [•] indicates the real part of the complex number, and Im [•] indicates the imaginary part of the complex number.

Here, the integer subscript indicates the medium type. When a radio wave is incident on the second medium from the first medium, the Fresnel reflection coefficient is R _|| (TE incidence), R _⊥ (TM incidence), the relative complex refractive index is n ₁₂ , and the ratio of the first medium Permeability is μ ₁ , relative permittivity is ε ₁ , conductivity is σ ₁ , relative permeability of the second medium is μ ₂ , relative permittivity is ε ₂ , conductivity is σ ₂ , incident angle is θ, angle When the frequency is ω, the thickness is d, and the wavelength is λ, R _|| (TE incidence) and R _⊥ (TM incidence) are expressed by the following equations (4), (5), and (6) (for example, Non-patent document 2).

  Further, the transmission coefficient T is expressed by the following equation (7).

In equation (7), β is a function of the thickness d and the wavelength λ ₁ in the first medium. Further, r ₁₂ is the Fresnel reflection coefficient of the first medium with respect to the second medium given by Expression (4) or (5), and r ₂₃ is the Fresnel reflection of the second medium with respect to the third medium. It is a coefficient.
Further, t ₁₂ is the transmission coefficient of Fresnel when the incident wave is transmitted to the second medium from the first medium, t ₂₃ is Fresnel when the incident wave is transmitted into the third medium from the second medium Is the transmission coefficient. The above β, t _|| (TE incidence) and t _⊥ (TM incidence) are respectively expressed by the following equations (8), (9), and (10). t _|| and t _⊥ are respectively used as t ₁₂ and t ₂₃ when calculating the transmission coefficient using Equation (7) in the case of TE incidence and TM incidence.

Tetsuro Imai, Yuichiro Inukai, Teruya Fujii, “Indoor Area Estimation System Using Ray-Trace”, IEICE Transactions B, Vol. J83-B, No. 11, p.1565-1576, November 2000 Yoshio Hosoya, “Radio Wave Propagation Handbook”, REALIZE INC., P.234-240, 1999

  In the above-described conventional technology, if an indoor propagation model composed of information on the position of the terminal or AP, the layout of the shielding object, and the material can be accurately modeled in advance using CAD software or the like, using computer simulation, The received power at any point of the terminal or AP can be accurately estimated.

  However, among the parameters necessary for modeling the indoor propagation model, the furniture layout is unique to each building / room, and needs to be modeled by CAD software or the like for each building / room. In addition, the physical characteristics of a shield such as furniture vary depending on the manufacturer even if the same type of material is used. For this reason, in the prior art, it is difficult to accurately input the position and material of the fixture, and there is a problem that it is impossible to accurately estimate the received power at any point of the terminal or AP.

  In view of the above circumstances, the present invention provides a received power estimation apparatus and a received power estimation method capable of accurately estimating received power at an arbitrary point without inputting layout or material of a shield such as furniture. The purpose is that.

  One aspect of the present invention is based on the received power of a plurality of paths actually measured in a space including an indoor space where a shield is installed, and the received power of the path when the space is assumed to be a free space. A path transmission loss extraction unit that calculates transmission loss for each path and a partition of the indoor space with a mesh, and estimation of transmission loss for each mesh based on the transmission loss for each path calculated by the path transmission loss extraction unit A mesh transmission loss estimator that calculates a value, and a received power that calculates an estimated value of received power at an arbitrary point in the space based on the estimated transmission loss value for each mesh calculated by the mesh transmission loss estimator A reception power estimation apparatus comprising: an estimation unit.

  One embodiment of the present invention is the reception power estimation device described above, wherein the reception power estimation unit is generated based on a difference in transmission loss estimation values of the meshes estimated by the mesh transmission loss estimation unit. The layout data of the indoor space, the estimated value of the transmission loss of each mesh, the position of the wireless communication device subject to reception power estimation, the transmission antenna gain, the reception antenna gain of the wireless communication device subject to reception power estimation, Based on the transmission power and the transmission frequency, an estimated value of the reception power of the wireless communication device that is a reception power estimation target is calculated.

  One embodiment of the present invention is the reception power estimation device described above, which is input from data in which a mesh size, a distance between a terminal and an obstacle, a projected area of an obstacle on an estimation plane, and an estimation error are associated with each other. A mesh size determination unit that obtains a mesh size corresponding to a distance between the terminal and the shielding object, a projected area of the shielding object on the estimation plane, and an estimation error, and outputs the mesh size to the mesh transmission loss estimation unit; Features.

  One embodiment of the present invention is the above-described received power estimation apparatus, which includes a mesh size, a distance between a terminal and a shielding object, a projection area of the shielding object on an estimation plane, an estimation error, a recursive processing count, and a processing count. From the associated data, the distance between the input terminal and the shielding object, the projected area of the shielding object on the estimated plane, and the number of recursive processes corresponding to the estimation error and the mesh size for each processing number are acquired, and the mesh transmission A dynamic mesh size determination unit that outputs to a loss estimation unit; and a fixture position estimation unit that determines the presence or absence of an obstruction based on the estimated transmission loss value for each mesh calculated by the mesh transmission loss estimation unit. In addition, the mesh transmission loss estimation unit may adjust the number of processes until the number of processes for calculating the estimated value of the transmission loss value reaches the number of recursive processes output from the dynamic mesh size determination unit. Mesh size delimiting said interior space, and calculates the estimated value of the transmission loss of each section.

  One embodiment of the present invention is the above-described reception power estimation device, wherein a wireless usage range in the indoor space is specified based on terminal position information including a position and time of a wireless communication device used in the indoor space. Then, the radio wave utilization range estimation that estimates and outputs the measurement area of the received power necessary to determine whether the amount of interference with other wireless communication devices located in the vicinity of the indoor space is equal to or less than a predetermined value It further has a section.

  One embodiment of the present invention is the above-described reception power estimation apparatus, further comprising a delay profile estimation unit that estimates a delay profile based on reception power of a plurality of paths actually measured in the space, and the path transmission loss The extraction unit calculates a transmission loss for each path based on the delay profile estimated by the delay profile estimation unit and the received power of the path when the space is assumed to be a free space. And

  Further, one aspect of the present invention is the above-described reception power estimation device, wherein a reception data correlation matrix is calculated from a frequency data vector obtained by sampling frequency domain data of reception power measured in the space, A path separation unit that calculates a spatial spectrum from a received data correlation matrix; and a propagation delay estimation unit that estimates a propagation delay time corresponding to a peak value of the spatial spectrum calculated by the path separation unit, the delay profile The estimation unit calculates received power corresponding to the propagation delay time of each path estimated by the propagation delay estimation unit as the delay profile.

  One embodiment of the present invention is the above-described reception power estimation device, wherein the path transmission loss extraction unit receives a signal from a transmission point based on a position of a wireless communication device used for actual measurement of reception power in the space. A ray trace calculation unit that calculates a path that reaches a point, a reflection coefficient and a transmission coefficient in a multipath environment are set to 1, a path calculated by the ray trace calculation unit, and a transmission frequency used for actual measurement of received power Based on the propagation loss calculation unit for calculating the free propagation distance attenuation, the free propagation distance attenuation calculated by the propagation loss calculation unit, and the transmission antenna gain of the wireless communication device used for the actual measurement of received power A reception power calculation unit that calculates reception power of a reception point based on the reception antenna gain and transmission power, the reception power of the reception point calculated by the reception power calculation unit, and the delay B and a file subtraction estimator calculates the transmission loss of each of the paths on the basis of a difference between the received power obtained from the delay profile estimator, characterized in that.

  One embodiment of the present invention is a reception power estimation method executed by a reception power estimation apparatus, in which a path transmission loss extraction unit includes a plurality of paths measured in a space including an indoor space where a shield is installed. A path transmission loss extraction process for calculating a transmission loss for each path based on the received power and the received power of the path when the space is assumed to be a free space, and the mesh transmission loss estimation unit includes the indoor space A mesh transmission loss estimation process for calculating an estimated value of transmission loss for each mesh based on the transmission loss for each path calculated in the path transmission loss extraction process, and a received power estimation unit, Received power estimation that calculates an estimated value of received power at an arbitrary point in the space based on an estimated value of transmission loss for each mesh calculated in the transmission loss estimation process. A received power estimating method characterized by comprising the steps, a.

  According to the present invention, a different indoor space for each building / room is separated by a mesh, and the transmission loss value for each mesh is estimated from measured data, so that the layout or material of a shielding object such as furniture can be input at any point. It is possible to accurately estimate the received power.

It is a figure which shows the indoor propagation model with which the communication system by 1st Embodiment of this invention is a premise. It is a block diagram which shows the structure of the received power estimation apparatus by the same embodiment. It is a conceptual diagram which shows the model which divided | segmented the indoor space by the mesh by the same embodiment. It is a block diagram which shows the structure of the path | pass transmission loss extraction part by the embodiment. It is a flowchart for demonstrating operation | movement of the received power estimation apparatus by the embodiment. It is a flowchart for demonstrating operation | movement of the path | pass transmission loss extraction part by the embodiment. It is a conceptual diagram which shows the relationship of the mesh size with respect to the distance of the terminal of the reception power estimation object by the same embodiment, and a shield. It is a conceptual diagram which shows the positional relationship of the transmitting station used as a measurement radio | wireless communication apparatus and the receiving station, and a shield in the simulation using the receiving power estimation apparatus by the embodiment. It is a conceptual diagram which shows the positional relationship of the transmission station of the reception power estimation object in the simulation using the reception power estimation apparatus by the same embodiment, a receiving station, and an obstruction. It is a figure which shows the material of the shield used in the simulation using the received power estimation apparatus by the embodiment. It is a figure which shows the corresponding | compatible number of the permeation | transmission surface of the mesh in the simulation using the received power estimation apparatus by the embodiment. It is a figure which shows the output result of the mesh transmission loss estimation part in the simulation using the received power estimation apparatus by the embodiment. It is a figure which shows the complementary cumulative distribution function of the estimation error of the output result of a received power estimation part in a simulation using the received power estimation apparatus by the same embodiment, and a theoretical value. It is a figure which shows the structure of the received power estimation apparatus by 2nd Embodiment. It is a flowchart for demonstrating operation | movement of the received power estimation apparatus by the embodiment. It is a figure which shows the structure of the received power estimation apparatus by 3rd Embodiment. It is a flowchart for demonstrating operation | movement of the electromagnetic wave utilization range estimation part by the embodiment. It is a figure which shows the structure of the received power estimation apparatus by 4th Embodiment. It is a figure which shows an example of the data of the mesh size contained in the database which the dynamic mesh size determination part by the embodiment has memorize | stored. It is a figure which shows an example of the number of required measurement data contained in the database which the dynamic mesh size determination part by the embodiment has memorize | stored. It is a flowchart for demonstrating operation | movement of the received power estimation apparatus by the embodiment. It is a block diagram which shows the structure of the reception power estimation apparatus of a prior art. It is a block diagram which shows the structure of the reception power estimation part shown in FIG.

Embodiments of the present invention will be described below with reference to the drawings.
In this embodiment, by combining delay profile estimation, transmission loss extraction for each path, and transmission loss estimation for each mesh, a plurality of actually measured data is used to estimate a transmission loss value for each transmission surface divided by the mesh, The received power at an arbitrary place can be estimated.

[A. First Embodiment]
FIG. 1 is a block diagram showing an indoor propagation model premised on the communication system according to the first embodiment of the present invention. The indoor propagation model includes a wireless receiving station 301 and a transmitting station 302. In an indoor propagation model under a multipath environment in which radio waves transmitted from the transmission station 302 reach the reception station 301 through various paths, the reception station 301 receives direct waves transmitted from the transmission station 302. This direct wave passes through a shield such as furniture arranged indoors. Although the receiving station 301 is installed indoors in the figure, the receiving station 301 may be installed outdoors, the receiving station 301 may be installed outdoors, and the transmitting station 302 may be installed indoors. Good.

  FIG. 2 is a block diagram showing a configuration of the received power estimation apparatus 100 according to the first embodiment. The reception power estimation apparatus 100 includes a delay profile estimation unit 101, a path transmission loss extraction unit 102, a mesh size determination unit 103, a mesh transmission loss estimation unit 104, and a reception power estimation unit 105.

  The delay profile estimation unit 101 performs actual measurement data when measurement is performed while changing the positions of actual measurement wireless communication devices used as the receiving station 301 and the transmission station 302 (hereinafter referred to as “measurement wireless communication device”). Receive input. The actual measurement data indicates actual measurement values of the level and phase of the received signal and the known signal for each frequency channel between the actual measurement wireless communication apparatuses. Hereinafter, a case where a terminal (hereinafter, also referred to as “measurement terminal”) and an access point (AP) are used as an example of the actually measured wireless communication apparatus will be described. Note that either the terminal or the AP may be a transmitting station / receiving station.

  The delay profile estimation unit 101 performs correlation calculation on actually measured data including all samples of the received signal and the known signal by sliding correlation processing, and estimates and outputs the delay profile. The delay profile indicates the relationship between the delay time and the received power. The path transmission loss extraction unit 102 can freely move between the measurement terminal and the AP from the delay profile estimated by the delay profile estimation unit 101, the input position of the actual measurement terminal and AP, and the input transmission parameter of the actual measurement terminal. The transmission loss for each path when it is assumed to be a space is calculated. The path when it is assumed that the space between the actual measurement terminal and the AP is a free space corresponds to a direct wave path, that is, a path connecting the actual measurement terminal and the AP with a straight line. The transmission parameters include transmission antenna gain, reception antenna gain, transmission power, and transmission frequency.

The mesh size determination unit 103 sets a mesh size when the indoor space is divided by a mesh. The mesh transmission loss estimation unit 104 divides the indoor space to be modeled by a mesh having a mesh size set by the mesh size determination unit 103, and calculates the mesh from the total transmission loss for each path calculated by the path transmission loss extraction unit 102. Estimate the transmission loss value for each surface.
FIG. 3 is a diagram illustrating a model in which indoor space is divided by a mesh in the mesh transmission loss estimation unit 104. As shown in the figure, the indoor space to be modeled is divided by a mesh having the same size in the vertical, horizontal, and height.

  The reception power estimation unit 105 illustrated in FIG. 2 includes transmission loss values of each surface estimated by the mesh transmission loss estimation unit 104, the positions of the terminals and APs that are reception-power estimation target wireless communication devices, Using the transmission antenna gain, reception antenna gain, transmission power, and transmission frequency included in the transmission parameter of the power estimation target terminal, estimate the reception power of the reception power estimation target terminal or AP installed at an arbitrary point. Output.

  FIG. 4 is a block diagram of the path transmission loss extraction unit 102 according to the first embodiment. As shown in the figure, the path transmission loss extraction unit 102 includes a ray trace calculation unit 201, a propagation loss calculation unit 202, a received power calculation unit 203, and a subtracter 204. The ray trace calculation unit 201 calculates a direct wave path between the actual measurement terminal and the AP as a transmitted wave path reaching from the transmission point to the reception point from the position of the actual measurement terminal and the AP when the actual measurement data is obtained. ,Output. The propagation loss calculation unit 202 sets the reflection coefficient, transmission coefficient, and diffraction coefficient to 1, and determines the free propagation of each path from the transmitted wave path output from the ray trace calculation unit 201 and the transmission frequency included in the transmission parameter. Calculate and output the distance attenuation.

  The reception power calculation unit 203 uses the free path distance attenuation amount of each path output from the propagation loss calculation unit 202 and the transmission antenna gain, the reception antenna gain, and the transmission power included in the transmission parameter, and uses free space. Is calculated for each path and output. The subtractor 204 calculates the difference between the calculation result of the reception power calculation unit 203 and the delay profile estimated by the delay profile estimation unit 101, and calculates and outputs the total transmission loss value for each path.

Next, the operation of the received power estimation apparatus 100 according to the first embodiment will be described.
FIG. 5 is a flowchart for explaining the operation of the reception power estimation apparatus 100 according to the first embodiment. In the first embodiment, a method of calculating a delay profile from time domain data is adopted. The received power estimation apparatus 100 receives actual measurement data, the position of the actual measurement terminal / AP used to acquire the actual measurement data, and the transmission parameters of the actual measurement terminal.

  First, the delay profile estimation unit 101 performs correlation calculation on actually measured data including all samples of the received signal and the known signal by sliding correlation processing, and estimates a delay profile (step S10). Conventional techniques are used for this estimation, and there are two methods for estimating the delay profile according to the prior art: a technique using time domain data and a technique using frequency domain data. In the method using time domain data, the received signal and the known signal are subjected to correlation calculation, the received signal pilot is divided by the transmitted signal pilot, the transfer function is obtained, and the obtained transfer function is subjected to inverse discrete Fourier transform, etc. To obtain a delay profile. On the other hand, in the method using frequency domain data, a delay profile can be obtained by a method of performing inverse discrete Fourier transform from a frequency spectrum, a high resolution method, etc. (for example, Reference 3: Shiki Shibata, “Delay Profile Estimation in OFDM Transmission”). Law ”, Journal of the Institute of Image Information and Television Engineers, Vol.60, No.10, p.1672-1680, 2006).

  The path transmission loss extraction unit 102 determines the delay profile estimated by the delay profile estimation unit 101 in step S10, the position of the actually measured terminal / AP, the transmission antenna gain, the reception antenna gain, the transmission power, and the transmission frequency included in the transmission parameters. Then, the total value of the transmission loss of the path is calculated and output (step S11).

Here, the operation of the path transmission loss extraction unit 102 will be described in detail.
FIG. 6 is a flowchart for explaining detailed operations in step S11 of the path transmission loss extraction unit 102 according to the first embodiment. First, the ray trace calculation unit 201 calculates a path connecting the position of the actual measurement terminal and the position of the AP assuming a free space, that is, a path of a transmitted wave that reaches from the transmission point to the reception point, and performs propagation loss. It outputs to the calculation part 202 (step S20). The propagation loss calculation unit 202 sets the reflection coefficient, the transmission coefficient, and the diffraction coefficient to 1, and reduces the free propagation distance from the transmitted wave path output from the ray-trace calculation unit 201 and the transmission frequency included in the transmission parameter. The amount is calculated and output (step S21).

The reception power calculation unit 203 receives the reception point using the free propagation distance attenuation calculated by the propagation loss calculation unit 202 and the transmission antenna gain, reception antenna gain, and transmission power included in the transmission parameters of the actually measured terminal. Power is calculated for each path and output (step S22).
The subtractor 204 calculates the total transmission loss value for each path by calculating the difference between the received power of each path calculated by the propagation loss calculation unit 202 and the delay profile estimated by the delay profile estimation unit 101. And output (step S23).

Next, the operation of the path transmission loss extraction unit 102 in steps S21 to S23 will be described in detail using mathematical expressions. With the reflection coefficient, transmission coefficient, and diffraction coefficient as 1, the distance attenuation L _i0 of free propagation of the i-th transmitted wave is expressed by the following equations (11) and (12). Here, i is the path and transmitted wave number, s _{i, 1} is the distance of the i-th transmitted wave path, f is the transmission frequency, c is the speed of light, k is the wave number, and E _i is the electric field strength of the i-th transmitted wave. It is. J is an imaginary unit, Re [•] indicates a real part of a complex number, and Im [•] indicates an imaginary part of the complex number. s _{i, 1} is calculated from the position of the actual measurement terminal and the AP. The wave number k is calculated by 2π / λ using the wavelength λ calculated from the transmission frequency included in the transmission parameter of the actually measured terminal.

The received power P _r0 for free propagation of the i th transmitted wave is expressed by the following equation (13). P _t is the transmission power, G _t is the transmission antenna gain, and G _r is the reception antenna gain, which are obtained from the transmission parameters of the actually measured terminal.

The total transmission loss Z _i [dB] of the i-th transmitted wave can be estimated using the received power P _{r, i} of the i-th transmitted wave as shown in the following equation (14). The received power _{Pr, i} is the received power value of the main wave of the i-th path indicated by the delay profile.

In step S21, the propagation loss calculation unit 202 calculates the distance attenuation L _i0 of free propagation of each transmitted wave using the above equations (11) to (12). In step S22, the reception power calculation unit 203 Uses the above equation (13) to calculate the free propagation received power _Pr0 of each transmitted wave. In step S23, the subtractor 204 calculates the total transmission loss Z _i of each transmitted wave according to the above equation (14).

Returning to FIG. 5, the description of the operation of the received power estimation apparatus 100 will be continued.
The mesh size determining unit 103 stores mesh size data indicating the relationship between the distance between the terminal and the shielding object with respect to the mesh size, the projected area of the shielding object on the estimated plane, and the allowable error. This mesh size data is data created based on estimation results of estimation performed in the past. In step S12, the mesh size determination unit 103 receives the input of the distance between the terminal and the shielding object with respect to the mesh size, the projection area of the shielding object on the estimated plane, and the allowable error, and the mesh size corresponding to the input information. From the mesh size data and output to the mesh transmission loss estimation unit 104.

FIG. 7 shows the relationship of the mesh size with respect to the distance between the received power estimation target terminal and the shielding object when the allowable error is 2 dB (decibel) and the projected area of the shielding object on the estimation plane is 1.275 m ² . At this time, if the distance between the terminal and the shielding object is 0.5 m, the mesh size is 0.41 m.

In FIG. 5, the mesh transmission loss estimation unit 104 calculates each surface for each mesh from the mesh size output from the mesh size determination unit 103 and the total transmission loss for each path output from the path transmission loss extraction unit 102. The transmission loss value is output (step S12).
Here, the operation of the mesh transmission loss estimation unit 104 will be described in detail using mathematical expressions.

Mesh transmission loss estimating unit 104, an indoor space to model separated by mesh with a mesh size that is output from the mesh size determining unit 103 estimates a transmission loss value M _h of each transmission surface of each section. I is the total number of paths, H is the total number of transmission surfaces, X _{i, h} = 1 if the i th transmitted wave is transmitted through the h th transmission surface, X _{i, h} = 0 if it is not transmitted, i th The transmission coefficient when the transmitted wave is transmitted through the h-th transmission surface is M _h , and the evaluation function is defined as in the following equation (15).

While satisfying these relational expressions, when a combination of the transmission coefficient M _h and X _{i, h} that minimizes the evaluation function shown in Expression (15) is obtained, each mesh whose transmission coefficient M _h satisfies the expression Loss allocation to each transmission surface, and can be analyzed by using a simplex method, a Newton method, a genetic algorithm, or the like. The initial value used in the analysis may be randomly selected in the range from the minimum value to the maximum value of the total transmission loss Z _i of the i-th transmitted wave.

Note that any of the following formulas (16), (17), and (18) may be used as the evaluation function instead of the formula (15). Note that V _i in the equations (17) and (18) is the true value of Z _i , and V _i = 10 ^ (− Z _i / 20).

  The mesh transmission loss estimation unit 104 calculates a transmission coefficient for each transmission surface of each mesh using Expression (15) (or Expression (16), (17), or (18)). Thereby, for example, in the mesh at a position corresponding to the shielding object, a transmission coefficient corresponding to the material of the shielding object is obtained. That is, since the mesh at the position corresponding to the shielding object is specified from the difference in the transmission coefficient between adjacent meshes, data corresponding to the layout data created by the conventional CAD can be obtained.

The reception power estimation apparatus 100 receives input of the reception power estimation target terminal and AP position, which are installed at arbitrary points in the space to be modeled, and the transmission parameters of the reception power estimation target terminal. The reception power estimation unit 105 generates layout data based on the transmission loss value of the transmission surface for each mesh output from the mesh transmission loss estimation unit 104, and uses the generated layout data to perform conventional technology (Non-Patent Document 1). Is applied to estimate the received power of the target wireless communication apparatus set at an arbitrary point (step S13). That is, the received power estimation unit 105 performs a geometrical analysis of the ray trajectory based on the layout data and the position of the received power estimation target terminal and AP by the same process as the prior art ray trace calculation unit 902 shown in FIG. Trace the pathologically, calculate and output the path from the transmission point to the reception point. The reception power estimation unit 105 sets the reflection coefficient R _{i, h, l} = 1, diffraction coefficient D _{i, h, n} = 1, and uses the transmission parameter of the terminal that is the reception power estimation target, and the equation described in the related art. From (1), (2), and (3), the reception power on the reception point side is estimated among the reception power estimation target terminals and APs set at arbitrary points. For the transmission coefficient T _{i, h, m} , the transmission coefficient of the transmission surface of each mesh calculated in step S12 is used. s _{i, 1} , s _{i, p} are obtained from the layout data and the positions of the terminal and the AP, and P _t , G _t , G _r are obtained from the transmission parameters. k is obtained by 2π / λ using the wavelength λ calculated from the transmission frequency included in the transmission parameter.

  The Fresnel equation is defined for TE wave incidence and TM incidence, and is applicable when the incident surface is perpendicular to the reflection / transmission surface. Therefore, when oblique incidence is considered with respect to the reflection / transmission surface, it is necessary to obtain the polarization ratio from the position of the terminal and AP of the received power estimation target and the normal vector of the transmission / reflection surface (for example, reference document) 4: Masahiro Takeshita, Tokio Taga, Tetsuro Imai, “Examination of cross polarization characteristics in indoor propagation environment”, IEICE Transactions B).

Next, the simulation result by the received power estimation apparatus 100 of this embodiment is shown.
FIG. 8 is a conceptual diagram showing a positional relationship between a transmitting station and a receiving station as an actual measurement wireless communication apparatus used for simulation and a shielding object. The figure shows the positional relationship when viewed from above, and a 3 m square room is provided with a shielding object having a height of 0.3 m, a width of 0.3 m, and a height of 1.5 m. In addition, an actual measurement wireless communication apparatus used as a transmission station and a reception station was arranged while changing its position in an 8 m square area around the room, and a direct wave was actually measured.

  FIG. 9 is a conceptual diagram showing the positional relationship between a transmission station and a reception station that are reception power estimation targets used in the simulation, and the shield. This figure shows the positional relationship when viewed from above. As shown in the figure, terminals as transmitting stations were randomly placed in a 3 m square room shown in FIG. 8, and the received power of the receiving station on the estimation plane was estimated. The estimated plane was a plane 0.1 m away from the room. The mesh transmission loss estimation unit 104 divides the periphery of the shielding object with a mesh, as indicated by a dotted line, and calculates the transmission loss of each transmission surface of each mesh. Let the meshes around the shield be mesh B1, mesh B2, mesh B3, and mesh B4.

  FIG. 10 is a diagram showing the material of the shield used in the simulation. The material of the shield shown in FIG. 10 is described in Reference 5 (Rec. ITU-R P.1238, “Propagation data and prediction methods for the planning of indoor radio communication systems and radio local area networks in the frequency range 900 MHz to 100 GHz. , "Recommendation ITU-R, p.12-14).

FIG. 11 is a diagram showing the corresponding numbers of the transmission surfaces of the mesh in this simulation.
In FIG. 9, the transmission surface of the mesh indicated by the dotted line in FIG. 9 is shown. As shown in the figure, mesh B1 has transmission surfaces C1, C3, C4, C6, mesh B2 has transmission surfaces C2, C4, C5, C7, and mesh B3 has transmission surfaces C6, C8, C9, C11 and the mesh B4 has transmission surfaces C7, C9, C12, and C10.

  FIG. 12 is a diagram illustrating a result output by the mesh transmission loss estimation unit 104 as a simulation result of the received power estimation apparatus 100 according to the first embodiment. As shown in the figure, transmission loss of each of the transmission surfaces C1 to C12 is obtained.

  FIG. 13 shows a complementary cumulative distribution function (CCDF) of the estimation error between the result output from the received power estimation unit 105 as the simulation result of the received power estimation apparatus 100 according to the first embodiment and the theoretical value. FIG. The CCDF of the received power estimation error shown in the figure is the theoretical value of the received power in the reception estimation plane when the terminals are randomly placed in the room as shown in FIG. 9, and the received power estimated by the received power estimation unit 105. It is CCDF of an error with electric power.

  As is apparent from FIGS. 12 and 13, the received power estimation apparatus 100 can estimate the transmission loss value for each mesh using measured data, and can estimate received power at an arbitrary place using computer simulation. . That is, as shown in FIG. 12, the mesh transmission loss estimation unit 104 determines the transmission loss of each of the transmission surfaces C1 to C12 in order from the transmission surface C1, 0.4, 5.3, 0, 3.4, 5.. It was estimated as 0, -0.2, 3.5, 0, -0.2, 0.3, -0.3, -0.1 (dB). Also, the received power estimation unit 105 estimates that the received power estimation error is 0.42 (dB) even when the CCDF is 0.01.

[B. Second Embodiment]
In the first embodiment, the delay profile is generated from the time domain data. In the second embodiment, the delay profile is calculated using the frequency domain data. Hereinafter, the difference from the first embodiment will be mainly described.

  FIG. 14 is a block diagram showing the configuration of the received power estimation apparatus 100a according to the second embodiment of the present invention. The same components as those of the received power estimation apparatus 100 of the first embodiment shown in FIG. A description thereof will be omitted. The received power estimation apparatus 100a according to the second embodiment includes a path separation unit 601, a propagation delay estimation unit 602, a delay profile estimation unit 603, a path transmission loss extraction unit 102, a mesh size determination unit 103, a mesh transmission loss estimation unit 104, And a received power estimation unit 105.

The path separation unit 601 samples the actually measured frequency domain data at an appropriate sampling frequency (for example, the bandwidth of the OFDM signal), and calculates a reception data correlation matrix from the obtained frequency data vector. The path separation unit 601 calculates a reception data correlation matrix from the transmission frequency and the frequency bandwidth, and calculates and outputs a spatial spectrum from the calculated reception data correlation matrix. As a method for calculating the spatial spectrum from the received data correlation matrix, a high resolution technique such as MUSIC (MUltiple SIgnal Classification) method or ESPRIT (Estimation of Signal Parameters via Rotation Invariance Techniques) method (for example, Reference 6: Frantz Bouchereau, David Brady , and Colin Lanzl, “Multipath Delay Estimation Using a Superresolution PN-Correlation Method”, IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 49, NO. 5, MAY 2001). At this time, the spatial averaging method (for example, Reference 7: Naohisa Goto, Masao Nakagawa, Seihiko Ito, “Antenna / Wireless Handbook”, Ohmsha, p.457-459) is used to suppress the correlation of received data. It is also possible to do. The propagation delay estimation unit 602 differentiates the spatial spectrum output from the path separation unit 601 and estimates the propagation delay time corresponding to the peak value of the spatial spectrum. The delay profile estimation unit 603 calculates received power corresponding to the propagation delay time of each path and outputs a delay profile.
Next, the operation of the received power estimation apparatus 100a will be described.

  FIG. 15 is a flowchart for explaining the operation of the received power estimation apparatus 100a according to the second embodiment. As described above, in the second embodiment, the delay profile is calculated using the frequency domain data. The received power estimation apparatus 100a receives the actual measurement data, the position of the actual measurement terminal / AP used to acquire the actual measurement data, and the transmission parameters of the actual measurement terminal. The actual measurement data is frequency domain data of received power measured while changing the position of the actual measurement terminal / AP.

  The path separation unit 601 calculates a reception data correlation matrix from a frequency data vector obtained by sampling the actually measured frequency domain data at an appropriate sampling frequency (for example, the bandwidth of an Orthogonal Frequency Division Multiplexing (OFDM) signal) ( Step S30). The path separation unit 601 calculates and outputs a spatial spectrum from the received data correlation matrix using a high resolution method such as the MUSIC method or the ESPRIT method (step S31).

  Next, the propagation delay estimation unit 602 differentiates the spatial spectrum output from the path separation unit 601 to estimate and output the propagation delay time corresponding to the peak value of the spatial spectrum (step S32). The delay profile estimation unit 603 calculates received power corresponding to the propagation delay time of each path, and estimates and outputs the delay profile (step S33).

Here, the operation when the MUSIC method of the path separation unit 601, the propagation delay estimation unit 602, and the delay profile estimation unit 603 is used will be described in detail using mathematical expressions as an example.
The number of incoming waves, which is the total number of paths with different delay times between the measurement terminal and the AP, is I, the frequency data vector is x (f), and the mode vector of the i-th (i = 1 to I) path is a (τ _i ). If the sampling number is N, the sampled frequency is f _n (n = 1 to N), the frequency spectrum of the frequency f _n is s (f _n ), and the noise is n (f), the frequency bandwidth ΔF (= f _N− f ₁ ), a frequency data vector x (f) composed of N pieces of data sampled at a frequency interval Δf (OFDM signal bandwidth) is expressed by the following equation (19). It represents with Formula (20), (21), (22).

By sampling the frequency domain data at a frequency interval Δf (the bandwidth of the OFDM signal), a frequency data vector x (x (f) in equation (19)) is obtained, and the received data correlation matrix R _xx is the frequency data. Obtained by taking the ensemble average of vectors.

The reception data correlation matrix R _xx can be divided as shown in the following equations (24) to (26) using the eigenvalue λ _i and the eigenvector e _i .

Using the mode vector a and (tau) noise eigenvectors _{E N,} can space the spectrum _{P MUSIC} the MUSIC algorithm (tau) is defined as the following equation (27).

By differentiating P _MUSIC (τ), the delay time τ _i when taking the peak value for the i-th path can be calculated. The signal correlation matrix S corresponding to the delay time is expressed by the following equation (28).

As shown in the following equation (29), taking diagonal h _i of the signal correlation matrix S, pass the received power h is obtained.

  Assuming that δ (t) is a delta function, the delay profile h (t) is obtained by the following equation (30).

In step S30, the path separation unit 601 calculates the reception data correlation matrix R _xx using equation (23), and in step S31, the spatial spectrum P _MUSIC (τ) is calculated using equations (24) to (27). calculate. In step S32, the propagation delay estimation unit 602 differentiates the spatial spectrum P _MUSIC (τ) obtained by Expression (27) to calculate a delay time, and calculates the signal correlation matrix S by Expression (28). In step S33, the delay profile estimation unit 603 calculates the delay profile h (t) using the equations (29) to (30).

  The subsequent processing is the same as the operation after step S11 of the received power estimation apparatus 100 of the first embodiment shown in FIG. That is, the path transmission loss extraction unit 102, the delay profile output from the propagation delay estimation unit 602, the position of the actual measurement terminal and AP, the transmission antenna gain, the reception antenna gain, the transmission power, and the transmission frequency included in the transmission parameter Then, the total value of transmission loss for each path is calculated and output (step S34).

The mesh size determination unit 103 sets the mesh size in advance based on the mesh size data indicating the relationship between the distance between the terminal and the shielding object with respect to the mesh size, the projected area of the shielding object on the estimated plane, and the allowable error. deep. The mesh transmission loss estimation unit 104 transmits a transmission coefficient that satisfies the relational expression (15) from the total value of the mesh size output from the mesh size determination unit 103 and the transmission loss for each path output from the path transmission loss extraction unit 102. Among the combinations of M _h and X _{i, h,} a combination that minimizes the evaluation function of Expression (15) is selected (step S35). Analysis can be performed by using a simplex method, a Newton method, a genetic algorithm, or the like.

  The reception power estimation unit 105 outputs the transmission loss value of each mesh surface output from the mesh transmission loss estimation unit 104, the input received power estimation target terminal / AP position, and the transmission power estimation target terminal transmission parameter. A reception power estimation target terminal set at an arbitrary point from Equation (1), Equation (2), and Equation (3) using the transmission antenna gain, reception antenna gain, transmission power, and transmission frequency included in And the reception power on the reception point side of the AP is estimated (step S36).

  According to the above-described embodiment, the indoor space is divided by a mesh, and the transmission loss for each mesh is estimated from a plurality of actually measured data. -It is possible to accurately model indoor propagation unique to each room and accurately estimate the received power at an arbitrary point.

[C. Third Embodiment]
The indoor propagation environment model in the third embodiment includes an AP that is a reception power estimation target in addition to the indoor environment model of FIG. Each reception power estimation target AP is connected to a centralized control station via an optical fiber or the like, and transmission timing, channel, transmission power, and the like are collectively controlled. At this time, the centralized control station controls the frequency, transmission power, and antenna directivity of each AP so as not to interfere with each other between the APs, so that the signal level is reduced to a specified value or less at the usage boundary. In this way, a state in which the radio wave arrival ranges of the APs do not overlap with each other is defined as a radio wave closed space.

  In the third embodiment, on the premise that the radio wave closed space is used according to the radio wave usage distribution of the user, the radio use range is estimated, the layout estimation area having a high priority is estimated when the radio wave closed space is formed, and AP A reception power estimation device for efficiently acquiring actual measurement data necessary for forming a closed radio wave space by prompting a user or a maintenance person to acquire actual measurement data in a layout estimation area having a high priority estimated explain.

  FIG. 16 is a block diagram showing the configuration of the received power estimation apparatus 100b according to the third embodiment of the present invention. The same components as those of the received power estimation apparatus 100 of the first embodiment shown in FIG. A description thereof will be omitted. The received power estimation apparatus 100b according to the third embodiment includes a delay profile estimation unit 101, a path transmission loss extraction unit 102, a mesh size determination unit 103, a mesh transmission loss estimation unit 104, a reception power estimation unit 105, and a radio wave use range estimation. Part 308. The reception power estimation unit 105 of this embodiment has the same function as the reception power estimation unit 105 (FIG. 2) of the first embodiment, but in this embodiment, the configuration of the reception power estimation unit 105 will be described in more detail. The reception power estimation unit 105 includes a ray trace calculation unit 305, a propagation loss calculation unit 306, and a reception power calculation unit 307.

  The ray trace calculation unit 305 regards the radio wave radiated from the transmission point in a spherical shape as a ray, and generates layout data based on the transmission loss value of the transmission surface for each mesh output from the mesh transmission loss estimation unit 104. Based on the generated layout data and the position of the received power estimation target terminal, the ray trajectory is traced geometrically, and a path from the transmission point to the reception point is output.

  The propagation loss calculation unit 306 calculates a transmission coefficient, a reflection coefficient, an opening coefficient, and an attenuation amount due to the distance for each path from the ray path output from the ray trace calculation unit 305, the shielding material, and the transmission frequency. calculate. Note that the propagation loss calculation unit 306 calculates the attenuation amount by the same operation as the propagation loss calculation unit 903. The propagation loss calculation unit 306 outputs the calculated attenuation amount to the received power calculation unit 307.

  The reception power calculation unit 307 calculates the reception power at the reception point using the attenuation output from the propagation loss calculation unit 306 and the transmission antenna gain, reception antenna gain, and transmission power included in the transmission parameter. Output. The reception power calculation unit 307 calculates reception power by the same operation as the reception power calculation unit 904.

  The radio wave usage range estimation unit 308 identifies the user's radio usage range based on the terminal location information. The radio wave usage range estimation unit 308 estimates a layout estimation area from the specified radio usage range and indoor floor plan data, and outputs priority area information indicating the estimated layout estimation area. In addition, when the priority area information is output, the radio wave usage range estimation unit 308 outputs the priority area information to a user such as a measurer by displaying an image in which the priority area information is superimposed on the indoor floor plan data. Also good.

  FIG. 17 is a flowchart for explaining the operation of the radio wave usage range estimation unit 308 according to the third embodiment. The radio wave utilization range estimation unit 308 inputs terminal position information acquired using a positioning method such as GPS or sound waves, and indoor floor plan data. The terminal location information includes information indicating the location of the terminal and information indicating the time when the information is acquired. The radio wave usage range estimation unit 308 expresses the usage range of the terminal by a circle whose radius is the measurement error for each positioning method centered on the location of the terminal from the terminal location information. At this time, based on the terminal location information acquired at time t, a space where the circle of the terminal usage range for the past n times of positioning overlaps with the circle of the terminal usage range at time t is calculated and determined in advance. The space exceeding the threshold value is output as the user's wireless usage range (step S41). The radio wave usage range estimation unit 308 calculates a radio usage range using a known technique (for example, Reference 8: Naoji Yamada, Yoshinori Hamada, Masateru Minami, Hiroyuki Morikawa, “GPS-equipped mobile phone for outdoor action support” "Sequential refining method of moving route using", IPSJ Journal, Vol.52, No.6, p.1951-1967, July 2011).

  Next, the radio wave usage range estimation unit 308 estimates a region where measured data is preferentially acquired from the estimated wireless usage range and indoor floor plan data, and outputs the estimated region as a layout estimation region (step S42). ). In the radio wave closed space, the transmission power value is determined in accordance with a path with a small propagation loss in order to make the amount of interference below a specified value at the boundary. Therefore, the radio wave usage range estimation unit 308 estimates a region where the propagation loss from the user's wireless usage range to the boundary is smaller than the set value, and sets the acquisition priority of actual measurement data in the estimated region to be high.

The acquisition area estimation operation by the radio wave usage range estimation unit 308 will be described in detail using mathematical expressions. First, a point (a ₀ , b ₀ , c ₀ ) closest to the use boundary in the wireless use range is calculated. A distance R between the point (a ₀ , b ₀ , c ₀ ) and an arbitrary point (a, b, c) on the usage boundary is expressed by the following equation (31).

The frequency of the wireless system to be used is f, the transmission loss of general residential building materials is L, and the number of transmissions of building materials on a straight line connecting points (a ₀ , b ₀ , c ₀ ) and any point on the usage boundary as N, the propagation loss _{L R} from the point _{(a 0, b 0, c} 0) to any point of use boundary is calculated using the following equation (32). The radio frequency is acquired by AP spectrum sensing or the like.

On the other hand, the propagation distance of the minimum value of R and R _0, the transmission loss of the propagation distance R ₀ become available point and the point on the boundary _{(a 0, b 0, c} 0) and building materials made on a straight line connecting the L ', The transmission number is N ₀ , and the propagation loss L _R0 represented by the following equation (33) is used as a threshold value. The transmission loss L ′ is input by the user of the received power estimation apparatus 100b. When there are a plurality of wireless usage ranges, the above processing is performed in each wireless usage range.

Telecommunications range estimation unit 308 compares the threshold value set in advance of the formula (33), and a propagation loss L _R calculated by the equation (32), the propagation loss L _R is the propagation loss L _A region smaller than _R0 (threshold) is set as a layout estimation region. Next, the radio wave usage range estimation unit 308 outputs notification information indicating that the measured data is acquired with priority in the set layout estimation region and notifies the measurer (step S43). The actual measurement data acquired by the measurer is input to the delay profile estimation unit 101. The received power estimation apparatus 100b accepts measurement data measured by the measurer according to the notification information, and estimates received power in the same manner as the received power estimation apparatus 100 of the first embodiment.

  In this way, the received power estimation apparatus 100b according to the third embodiment determines whether or not the amount of interference with respect to another radio wave closed space is equal to or less than a specified value when the radio wave closed space is set and used indoors. Propagation samples required for forming a closed radio wave space by estimating the area to acquire the actual measurement data necessary to perform based on the wireless usage range and encouraging the measurer to acquire the propagation samples in that area Can be obtained efficiently. For example, when forming a radio wave closed space, it is necessary to estimate the layout of the whole area of the radio wave closed space in order to estimate the amount of interference on the usage boundary with other radio wave closed spaces. It was necessary to obtain the actual measurement data at. However, by using the received power estimation apparatus 100b of the third embodiment, it is possible to efficiently acquire actually measured data necessary for forming the radio wave closed space.

[D. Fourth Embodiment]
In the fourth embodiment, it is necessary to estimate the received power by subdividing the mesh size in stages and limiting the position of the shielding object, thereby omitting the mesh transmission loss estimation in the space where the shielding object does not exist. A received power estimation apparatus capable of reducing the absolute amount and the calculation amount of actually measured data will be described.

  FIG. 18 is a block diagram showing the configuration of the received power estimation apparatus 100c according to the fourth embodiment of the present invention. The same components as those of the received power estimation apparatus 100b of the third embodiment shown in FIG. A description thereof will be omitted. The received power estimation apparatus 100c in the fourth embodiment includes a delay profile estimation unit 101, a path transmission loss extraction unit 102, a dynamic mesh size determination unit 401, a mesh transmission loss estimation unit 402, a fixture position estimation unit 403, a reception power estimation unit. 105, and a radio wave utilization range estimation unit 308. The reception power estimation unit 105 includes a ray trace calculation unit 305, a propagation loss calculation unit 306, and a reception power calculation unit 307.

  The dynamic mesh size determination unit 401 includes a mesh size, a distance between the received power estimation terminal and the shielding object, a projected area of the shielding object on the estimation plane, mesh size data indicating a relationship between allowable errors, an allowable error, the number of recursive processes, A database including a mesh size for each process and a required number of actually measured data indicating the relationship between the number of actually measured data required as a whole is stored in advance. This database is data created based on the estimated evaluation results previously performed on the computer.

FIG. 19 is a diagram illustrating an example of mesh size data included in the database stored in the dynamic mesh size determination unit 401 according to the fourth embodiment. The allowable error, the projected area of the estimation plane, the distance between the received power estimation terminal and the shielding object, and the mesh size are stored in association with each other. For example, the allowable post-difference “1.5 dB”, the projected area “1 m ² ”, the distance “0.2 m”, and the mesh size “0.2 m” are associated with each other.

  FIG. 20 is a diagram illustrating an example of the number of required actual measurement data included in the database stored in the dynamic mesh size determination unit 401 according to the fourth embodiment. The allowable post-difference, the number of recursive processes, the number of processes, the mesh size, and the number of actually measured data are stored in association with each other. For example, the allowable post-difference “1.5 dB”, the recursion processing count “3 times”, the processing count “second time”, the mesh size “0.3 m”, and the actually measured data count “8500” are associated with each other.

  The dynamic mesh size determination unit 401 accepts input of the distance between the terminal and the shielding object with respect to the mesh size, the projected area of the shielding object on the estimated plane, the allowable difference, and the required number of actually measured data. The dynamic mesh size determination unit 401 reads out the number of recursive processes corresponding to the received information and the mesh size corresponding to the number of processes from the stored database. The dynamic mesh size determination unit 401 outputs the read recursion processing count and the mesh size to the mesh transmission loss estimation unit 402.

  The mesh transmission loss estimation unit 402 calculates the mesh size of each surface for each mesh from the mesh size output from the dynamic mesh size determination unit 401 and the total transmission loss for each path output from the path transmission loss extraction unit 102. The transmission loss value is calculated and output to the ray trace calculation unit 305. Note that the transmission loss value of each surface for each mesh by the mesh transmission loss estimation unit 402 is calculated in the same manner as the mesh transmission loss estimation unit 104.

  The fixture position estimation unit 403 compares the transmission loss value of each surface for each mesh output from the mesh transmission loss estimation unit 402 with a predetermined threshold value. As the threshold value, for example, a typical value of transmission loss of building materials of a general house may be used, or a value measured in advance may be used. The fixture position estimation unit 403 outputs an estimated determination value indicating the determination result to the mesh transmission loss estimation unit 402.

  FIG. 21 is a flowchart for explaining the operation of the received power estimation apparatus 100c according to the fourth embodiment. The received power estimation apparatus 100c includes terminal position information, measured data, positions of the measured terminal and AP used to acquire the measured data, transmission parameters of the measured terminal, received power estimation target terminal / AP position, received power estimation target The transmission parameters of the terminal, the distance between the terminal and the shielding object with respect to the mesh size, the projected area of the shielding object on the estimated plane, the allowable difference, and the required number of actually measured data are input.

  The delay profile estimation unit 101, the path transmission loss extraction unit 102, the ray trace calculation unit 305, the propagation loss calculation unit 306, and the reception power calculation unit 307 perform the same processing as each unit according to the third embodiment. The delay profile estimation unit 101 performs correlation calculation on actually measured data including all samples of the received signal and the known signal by sliding correlation processing, estimates a delay profile, and outputs the estimated delay profile to the path transmission loss extraction unit 102 (step S50). ).

  If there is a delay profile estimated by the delay profile estimation unit 101, the path transmission loss extraction unit 102 determines the distance between the actual measurement terminal and the AP from the input actual measurement terminal and AP position and the input transmission parameter of the actual measurement terminal. The total value of transmission loss for each path when it is assumed that the space is free is calculated (step S51).

  The dynamic mesh size determination unit 401 accepts input of the distance between the terminal and the shielding object with respect to the mesh size, the projected area of the shielding object on the estimated plane, the allowable difference, and the required number of actually measured data. The corresponding number of recursive processes and the mesh size corresponding to the number of processes are read from the database and output to the mesh transmission loss estimation unit 402 (step S52).

  The mesh transmission loss estimation unit 402 uses the mesh size output from the dynamic mesh size determination unit 401 and the total value of transmission loss for each path output from the path transmission loss extraction unit 102 to calculate each surface for each mesh. A transmission loss value is output (step S53).

The mesh transmission loss estimation unit 402 divides the indoor space to be modeled by the mesh size output from the dynamic mesh size determination unit 401 (or the following equations (34) (or (35), (36), (37) Is used to calculate the transmission loss value M _h for each transmission surface of each mesh. I is the total number of paths, H is the total number of transmission surfaces, X _{i, h} = 1 if the i-th transmitted wave is transmitted through the h-th transmission surface, and X _{i, h} = 0 if it is not transmitted. The transmission coefficient when the i-th transmitted wave is transmitted through the h-th transmission surface is M _h , the estimation determination value α _h = 1 when the h-th transmission surface is estimated, and α _h = 0 when the estimation is not performed. . Note that, in the initial estimation, the estimation determination value α _h of all the transmission surfaces is 1.

  The mesh transmission loss estimation unit 402 determines whether or not the number of processes has reached the number of recursive processes (step S54). If the number of processes has not reached the number of recursive processes (step S54: NO), the process proceeds to step S55. Proceed to If the number of processes has reached the number of recursive processes (step S54: YES), the process proceeds to step S56.

The fixture position estimation unit 403 compares the transmission loss value of each surface for each mesh output from the mesh transmission loss estimation unit 402 with a threshold value. The fixture position estimation unit 403 sets the estimated determination value α _h to 1 when the transmission loss value exceeds the threshold value (α _h = 1), and estimates the estimated determination value when the transmission loss value is equal to or less than the threshold value. α _h is set to 0 (α _h = 0) (step S55), and the process returns to step S52. As a result, for example, the estimated determination value α _h is set to 1 in the mesh at the position where the shielding object is present. This process is repeated recursively while subdividing the mesh size step by step, and by gradually identifying the mesh at the position corresponding to the shielding object, the actual measurement data and calculation amount required for the entire process can be reduced. Can do.

  In step S56, the ray trace calculation unit 305 generates layout data based on the transmission loss value of the transmission surface for each mesh output from the mesh transmission loss estimation unit 402, and generates the generated layout data and the received power estimation target terminal. Based on the position, the ray trajectory is traced geometrically, and a path from the transmission point to the reception point is output. The propagation loss calculation unit 306 outputs a transmission coefficient, a reflection coefficient, a diffraction coefficient, and an attenuation amount due to a distance for each path from the ray path output from the ray trace calculation unit 305, the shielding material, and the transmission frequency. To do. The reception power calculation unit 307 calculates the reception power at the reception point using the attenuation output from the propagation loss calculation unit 306 and the transmission antenna gain, reception antenna gain, and transmission power included in the transmission parameter. Output.

  Through the above processing, the received power estimation apparatus 100c according to the fourth embodiment estimates the received power of the wireless communication apparatus (terminal and AP) that is a reception power estimation target set at an arbitrary point. In addition, since the mesh size is predetermined so that the mesh size is reduced as the number of processing increases, the mesh size is changed stepwise when estimating the received power, and the computation processing is performed on the space where there is no shielding object. Therefore, it is possible to reduce actual measurement data and calculation amount necessary for estimation of received power. In addition, when forming a closed radio wave space, it is possible to reduce the actual measurement data required to reduce the amount of interference to other adjacent radio wave closed spaces below the specified value, and to make the acquisition of the actual measurement data more efficient. Can do.

  Note that the radio wave utilization range estimation unit 308 provided in the received power estimation apparatus 100b according to the third embodiment may be applied to the received power estimation apparatus according to the first and second embodiments. The received power estimation apparatus according to the first and second embodiments determines the dynamic mesh size included in the received power estimation apparatus 100c according to the fourth embodiment instead of the mesh size determination unit 103 and the mesh transmission loss estimation unit 104. A unit 401, a mesh transmission loss estimation unit 402, and a fixture position estimation unit 403 may be provided.

  Delay profile estimation unit 101, path transmission loss extraction unit 102, mesh size determination unit 103, mesh transmission loss estimation unit 104, received power estimation unit 105, ray trace in the first, second, third, and fourth embodiments described above. Calculation unit 201, propagation loss calculation unit 202, received power calculation unit 203, subtractor 204, path separation unit 601, propagation delay estimation unit 602, delay profile estimation unit 603, ray trace calculation unit 305, propagation loss calculation unit 306, reception The functions of the power calculation unit, the radio wave use range estimation unit 308, the dynamic mesh size determination unit 401, the mesh transmission loss estimation unit 402, and the fixture position estimation unit 403 may be realized by a computer. In that case, a program for realizing this function may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Furthermore, the “computer-readable recording medium” dynamically holds a program for a short time like a communication line when transmitting a program via a network such as the Internet or a communication line such as a telephone line. In this case, a volatile memory inside a computer system serving as a server or a client in that case may be included and a program that holds a program for a certain period of time. The program may be a program for realizing a part of the functions described above, and may be a program capable of realizing the functions described above in combination with a program already recorded in a computer system.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes designs and the like that do not depart from the gist of the present invention.

  It can be used when estimating wireless reception power in a multipath environment.

100, 100a, 100b, 100c Received power estimation apparatus 101 Delay profile estimation unit 102 Path transmission loss extraction unit 103 Mesh size determination unit 104 Mesh transmission loss estimation unit 105 Reception power estimation unit 201 Ray trace calculation unit 202 Propagation loss calculation unit 203 Reception Power calculation unit 204 Subtractor 601 Path separation unit 602 Propagation delay estimation unit 603 Delay profile estimation unit 301 Reception station 302 Transmission station 305 Ray trace calculation unit 306 Propagation loss calculation unit 307 Reception power calculation unit 308 Radio wave use range estimation unit 401 Dynamic Mesh size determination unit 402 Mesh transmission loss estimation unit 403 Fixture position estimation unit 900 Reception power estimation device 901 Reception power estimation unit 902 Ray trace calculation unit 903 Propagation loss calculation unit 904 Reception power calculation unit

Claims (9)

Based on the received power of a plurality of paths measured in a space including an indoor space where a shield is installed, and the received power of the path when the space is assumed to be a free space, the transmission loss for each path is calculated. A path transmission loss extraction unit to calculate,
A mesh transmission loss estimation unit that divides the indoor space with a mesh and calculates an estimated value of transmission loss for each mesh based on the transmission loss for each path calculated by the path transmission loss extraction unit;
A received power estimating unit that calculates an estimated value of received power at an arbitrary point in the space based on an estimated value of a transmission loss value for each mesh calculated by the mesh transmission loss estimating unit;
A received power estimation apparatus comprising: The received power estimator includes layout data of the indoor space generated based on a difference in transmission loss estimates of the meshes estimated by the mesh transmission loss estimator, and estimated values of the transmission losses of the meshes. The radio communication of the reception power estimation target based on the position of the radio communication device of the reception power estimation target and the transmission antenna gain, reception antenna gain, transmission power, and transmission frequency of the radio communication device of the reception power estimation target Calculate an estimate of the received power of the device,
The received power estimation apparatus according to claim 1. From the data that associates the mesh size, the distance between the terminal and the shielding object, the projected area of the shielding object on the estimated plane, and the estimation error, the distance between the input terminal and the shielding object, the projected area of the shielding object on the estimated plane, And a mesh size determination unit that obtains a mesh size corresponding to the estimation error and outputs the mesh size to the mesh transmission loss estimation unit,
The received power estimation apparatus according to claim 1 or 2, wherein From the data that associates the mesh size, distance between the terminal and the shield, the projected area of the shield on the estimated plane, the estimation error, the number of recursive processes, and the number of processes, the distance between the input terminal and the shield, A projected area on the estimation plane, and a recursive processing count corresponding to the estimation error and a mesh size for each processing count, and a dynamic mesh size determination unit that outputs to the mesh transmission loss estimation unit,
Based on the estimated value of the transmission loss value for each mesh calculated by the mesh transmission loss estimation unit, a fixture position estimation unit that determines the presence or absence of an obstruction,
Further comprising
The mesh transmission loss estimator is
The indoor space is divided by the mesh size corresponding to the number of processes until the number of processes for calculating the estimated value of the transmission loss reaches the number of recursive processes output from the dynamic mesh size determination unit, and the transmission loss for each mesh is calculated. The received power estimation apparatus according to claim 1 or 2, wherein an estimated value is calculated. Based on terminal position information including the position and time of the wireless communication device used in the indoor space, the wireless use range in the indoor space is specified, and interference with other wireless communication devices located in the vicinity of the indoor space 4. A radio wave usage range estimation unit that estimates and outputs an actual measurement area of received power necessary for determining whether or not the amount is equal to or less than a predetermined value. The received power estimation apparatus according to Item 1. A delay profile estimation unit for estimating a delay profile based on the received power of a plurality of paths actually measured in the space;
The path transmission loss extraction unit calculates a transmission loss for each path based on the delay profile estimated by the delay profile estimation unit and the received power of the path when the space is assumed to be a free space. ,
The received power estimation apparatus according to any one of claims 1 to 5, wherein Calculating a received data correlation matrix from a frequency data vector obtained by sampling frequency domain data of received power actually measured in the space, and calculating a spatial spectrum from the received data correlation matrix; and
A propagation delay estimation unit that estimates a propagation delay time corresponding to the peak value of the spatial spectrum calculated by the path separation unit;
Further comprising
The delay profile estimation unit calculates received power corresponding to the propagation delay time of each path estimated by the propagation delay estimation unit as the delay profile.
The received power estimation apparatus according to claim 6. The path transmission loss extraction unit
Based on the position of the wireless communication device used for the actual measurement of the received power in the space, a ray trace calculation unit that calculates a path from the transmission point to the reception point;
Propagation loss for calculating the distance attenuation of free propagation based on the path calculated by the ray-trace calculator and the transmission frequency used for the actual measurement of received power, with the reflection coefficient and transmission coefficient in a multipath environment set to 1. A calculation unit;
Based on the free propagation distance attenuation calculated by the propagation loss calculation unit and the transmission antenna gain, reception antenna gain, and transmission power of the wireless communication device used for the actual measurement of received power, the received power at the reception point A received power calculation unit for calculating
A subtractor for calculating a transmission loss for each path based on a difference between the reception power of the reception point calculated by the reception power calculation unit and the reception power obtained from the delay profile estimated by the delay profile estimation unit; Comprising
The received power estimation apparatus according to claim 6 or 7, wherein: A received power estimation method executed by a received power estimation apparatus,
Based on the received power of the plurality of paths actually measured in the space including the indoor space where the shield is installed, and the received power of the path when the space is assumed to be a free space, the path transmission loss extraction unit, A path transmission loss extraction process for calculating transmission loss for each path;
A mesh transmission loss estimation unit, wherein the mesh transmission loss estimation unit divides the indoor space with a mesh and calculates an estimated value of the transmission loss for each mesh based on the transmission loss for each path calculated in the path transmission loss extraction process When,
A received power estimation process in which a received power estimation unit calculates an estimated value of received power at an arbitrary point in the space based on an estimated value of a transmission loss value for each mesh calculated in the mesh transmission loss estimation process;
A received power estimation method comprising:

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